Burner control apparatus



IENITIEIN TIMER W/ I T A T 5 U M H E H T v. R TATE BURNER CONTROLAPPARATUS Filed Aug. 22, 1941 BLEIWER EUNTRUL DNTR' DL RUUM THERMUETATLIMIT LIMIT E Feb. 27, 1945.

Patented Feb. 27, 1945 UNITED STATES "PATENT OFFICE".

2,370,205 r BURNER con'rnon APPARATUS Virgil Robins Tate, Milwaukee,Wis., asslgnor to Perfex Corporation, Milwaukee, Wis., a corporation ofWisconsin Application August 22,1941, Serial No. 407,867

Claims.

This invention relates in general to automatic control of fuel burnersand more particularly to control of oil burners of the pot orvaporization In this type of burner oil is fed into a pot type of retortin which it vaporizes, the vapor rising and mixing with air passingthrough perforations in the side walls of the burner pot, this forming.

effected by varying the oil supply to cause the tirely cut off when heatis not required, an igniter being pzbvidedfor igniting the fuel whenheat is required.

The present invention provides a simple and dependable control systemfor vaporization burners of the type having both'a blower and anigniter. The invention, however, is not limited to this type of burner,certain novel features or subcombinations being applicable to burnerswithout blowers, other features being applicable to burners withoutigniters, and some features being applicable to fuel burners in general.

In controlling burners of the type having a blower for forcing thedraft, it is desirable to operate the blower for a period of time afterthe oil supply is cutoff or reduced to low flame operation. Thisprovides for complete burning of the residual oil in the oil line orburner pot and reduces carbon formation therein. It is one object ofthis invention to provide an improved and simplified form of controlsystem for providing this operating sequence.

It is a further object of this invention to provide a control systemwhich acts upon call forheat to first provide a supply of oil to theburner and then after a period of time to place the blower intooperation. In burners having high-low flame type of control, thissequence permits the low flame to increase considerably in size and toheat-the burner pot nearer to vaporization temperature before the blowerstarts, thus in-.

' bers.

further function of making the operation of the igniter more positive.

It is a further object of the invention to provide a control system fora burner having an igniter and a fuel supply controller, which acts uponstarting of the burner to operate the igniterfor a period of time andthen render the igniter inoperative, the control system upon shuttingdown of the burneracting to maintain a supply of fuel for sustaining theflame until the igniter is conditioned for operation. This sequencepermits the use of a very simple form of control device for the igniterwhile atthe same time insuring that combustion willalways occur whenvthe burner is started.

Other objects of the invention will become apparent from the followingdescription and ap- Figure 1 In Fig. 1 reference character I indicatesgenerally a pot or vaporizati'on type of oil burner. The burnerillustrated is of known form and comprises a cup-shaped outer jacket 2which surrounds a perforated bowl or pot 3, an annular air space 4 beingprovided between these memouter jacket and supports a refractory ring 5at its upper end. The burner also includes'a fan or blower 6 which maybe of the centrifugal type including a motor 1 driving a rotor 8. Thisfan is connected by a blast tube 9 to the outer jacket 2, this tubedelivering air from the fan into the annular chamber 4' from which itflows through the perforations l0 into the interior of the bowl 3. Theburner l is also provided with a suitable igniter which may consist of aspark plug II screwed into a sleeve I 2 extending through the walls ofthe outer jacket and burner pot. Oil is supplied to the burner throughan oil line l3 through the blast tube 9 into the side wall of a Theconstant level valve l4 the burner bowl.

. may be of a form well known in the art and insuring that the forceddraft will not extinguish the flame-and also providing improved initialoperation of the burner. In burners provided with ignifers, thissequence of operation has the cludes a metering valve stem I! which ispositioned by a bimetal element l6, this element being subjected to theinfluence of an electric heater II. This arrangement constitutes a fuelThe bowl 3 is suitably secured within the supply control means forcontrolling the fiow of oilfrom a suitable source I! to the burner Inthe embodiment illustrated the bimetal element 16 warps upwardly whenthe heater I1 is energized, this raising the metering valve I5 andpermitting flow of oil to the burner. when the heater i1 is deenergizedthe bimetal element I 6 will cool down, lowering the valve stem i5 andbe of any suitable form and is shown diagrammatically as consisting of acoil 28 which operates through a suitable armature (not shown), a switcharm 80 cooperating with a contact 3|.

when the room thermostat calls for heat it closes the circuit for therelay coil 29 which causes the switch arm 30 to engage the contact 3|,

which as hereinafter described causes operation of the burner. When theroom thermostat becomes satisfied it breaks the circuit for coil 28,causing switch arm 30 to disengage contact 3| and discontinue burneroperation. Preferably or adiusted so that when the heaters 40 and 44 areenergized simultaneously, the blower timer will close its switch aperiod of time before the ignition timer opens its switch. These timersare also preferably designed or adjusted in a .manner so that when theheaters 4| and 44 are simultaneously deenergized, the ignition timerwill close its switch before the blower timer opens its switch. Thisrelation between the timers may be obtained by proper sizing of theheaters, by

proper adjusting of the distances between the fixed and movable contactsand/or by providing the proper relationship between the thermal massesOf the two active elements. This designing or adjusting of the thermaltimers so as to provide the above specified sequence may readily be doneby those familiar with the characteristics of timers of this type, andaccordingly no further explanation is necessary.

Operation I With the parts in the positions shown, the

room thermostat is satisfied, as indicated by the relay'switch arm beingdisengaged from contact II. The heaters 40 and 44 are now deenersizedand the timersare in their cold" positions. Thus the ignition switch 45-is closed the control system also includes a limit control 32 which isshown connected in line wire 21. This limit control may be responsive tothe temperature or pressure oi' the furnace heated by theburner andplaces the burner out of operation in the event that such temperature orpressure rises to a predetermined value.

The control system for the burner also includes air flow control meansincluding a blower timer 3! andadditionally includes an igniter-controlmeans comprising an ignition timer a. The blower timer may include anactive bimetal element 3! having a movable contact 38 which is adaptedto engage a fixed contact 89. The active bimetal element 41 is alsoprovided with an electric heater 40. This bimetalelement I1 ispreferably secured to a compensating bimetal element 4i which in turn isfixedly secured at its upper and the blowerswitch 38-" is open.

The room thermostat constitutes a heat demand responsive device. Whenthis device calls for heat, it energizes the relay II. This in- .stantlyenergizes the ignition transformer, the

elements 42 and 44, contacts 48 and 4l,'wire l5,

ignition transformer primary 44 and wire II to line wire 28.. Theenergizing circuit for theheatend. This compensating element 4| isarranged to act oppositely to the active element 31 and serves tocompensate the element 81 for changes in ambient temperature; When theheater 40 is deenergized the active element I1 becomes cool and assumesthe position shown in which the contact I! is disengaged from thecontact 49.

er I! extends from switch arm ll, through wires 54 and Ill, heater I!and wire I. line wire 28. The timer heaters and 44 a connected in seriesand are energized by a circuit extending from switch'arm 40 throughwires and I8, heater 44, wire 40,. heater 40 and wires II and 58 to linewire 28. From the description thus far it will be apparent that when theroom thermostat first calls for heat, the igniter is placed intooperation immediately and the oil valve heater is energized for causingopening of the oil valve, the blower motor 1 remaining at rest.

-When the oil valve opens,.oil fiows from the con- This preventsoperation of the fan, When the "active element 48 andan electric heater44 for heating the active element. The active element carries a movablecontact 4| cooperating with a fixed contact 48. When the active element.

is cold,due to heater 44 being deenergized, it assumes'the positionshown in which the movable contact 4| engages the fixed contact 48 whichpermits. energization of the primary 4. of an ignition transformer 49,thesecondary ll ofwhich is connected to the spark plug ll. When theactive element 4; .becomesmeated it warps to the right, causing themovable contact 44 to dis- Y engage the fixed contact 48 and thusprevent an ergization of the ignitiontrans'fomer.

timers ii and 34 are preferably-designed tolinewire2l.

stant level valve I4 through oil line ll into the burner pot, this oilbeing ignited by the spark produced by the spark plug I i; Due to theblower 1 remaining at rest, the small amount of oil in the burner pot isreadily ignited and the heat therefrom is retained inthe burner pot, thepot thereby becoming quickly heated. Thus the time is permitted to buildup considerably by natural draft before the blower is started, whichin-. sures that the flame will not be blown' out upon starting of theblower; P

Due to the timer heater 4. beingenergized, the timer switch 44- will becloud a period of time after the igniter and oil valve are enersized.This closure of the blower switch completes a circuit from line wire 21through wire as, bimetal elements 4l and 31,. contacts SI and ll, wire,blower motor I and, wires 44," and I. The blower is thus placed intooperation,v this providing a forced draft and in- ;creasing the ratefofburning of fuel. Due to the i nition timer contacts still being closed.the igniter II will continue 'to operate after the off the supply of oilto the burner.

blower starts. This is desirable as it provides further insurancethat'the burner will operate When the room thermostat becomes satisfiedit will deenergize the relay 2|, causing the switch arm 30 to disengagecontact 3|. This breaks the circuit for the fuel valve heater l1 andalso deenergizes the timer heaters 40 and 44. Thus the blower andignition timers begin cooling, and also the valve operating bimetal [6begins to cool. As the blower circuit through the blower timer isindependent of the relay 2 I, the blower 1 continues to operate. Theignition timer 38 after a short period of time closes its contacts 4546and then the bimetal element. It shuts The blower timer is designed soas to'maintain its contacts closed for a substantial period of timeafter the oil valve l becomes completely closed. This causes the fan tooperate until the residualoil in the line I3 is consumed. The blowerswitch 3839 then opens for stopping the blower. The burner then remainsat rest until the room thermostat again calls for heat and the cycleabove described is then repeated.

As pointed out above, the ignition timer is preferably desig ed so.as toclose its contacts before the valve positioning bimetal element 16completely closes the metering valve 15. This insures that oil will besupplied to the burner until the' ignition timer switch recloses. As aresuit a flame is always present in the burner pot to the settin of thelimit control 32.

switch blade 13 is adapted to cooperate with a fixed contact-14 andcontrols the blower motor 15. The switch blade 12 cooperates with afixed contact 16 forming a switch for controlling the igniter 11.- Thebimetal element 10 is provided with a heater 18. When this heater isdeener- Sized and the bimetal element 10 cold, this element assumes theposition shown in which the switch blade 12 is permitted to engage itsfixed contact 18 and" in which the switch blade 13 is pressed to theright out of engagement with the fixed contact 14; When the bimetalelement 10 heats under the action of heater 18 it warps to the leftwhich first permits the switch blade 13' to engage contact 14 and thenafter a period of time presses switch blade 12 away from contact 16.When the bimetal element 10 cools it warps to the right, which permitsreclo s i r igof the igniter switch 12-16 and later reopens the blowerswitch 1314.

The sequence of operation of the system shown in Fig. 2 is the same asthe system of Fig. 1. Thus when the room thermostat calls for'heat, theoil valve is energized immediately through a circuit extending from linewire 88 through the room thermostat 8|, wire 82, oilvalve 8.3 and wire,84 to line wire 85. Simultaneously the igniter at least until theignition timer is ready to begin a new cycle. This insures thatcombustion will always take place, irrespective of when the roomthermostat calls for heat. Thus if the thermostat calls for heat beforethe timer switch recloses, the igniter will not operate. However,

operation of the igniter is not necessary at such time as the flame isstill present in the burner pot. If the thermostat calls fo-rheat afterthe igniter switch is reclosed there may be no'fiame in the burner pot,but now the ignited is operative for igniting the fuel supplied. Whileit is preferable to utilize a slow acting all control valve as ll ra ed,this is not entirely essential and a quick acting valve such as asolenoid valve may be employed with like results if the oil line l3 hassufllcient capacit to maintain flame in the burner bowl until theignition timer recloses its switch.

It should be noted that if the furnace becomes heated beyond the settingof the safety or limit control 32, the burner will shut down in the 11is energizedby a circuit extending from the room thermostat throughwires 82 and 86, con

.tact 16, switch blade 12 .and igniter 11, to line wire 85. At the sametime the timer heater 18 is energized by a circuit extending from wire86 through heater 18, wire 81, ballast heater 88 and.wire 88 to linewire 85. Thus when the room thermostat calls for heat the oil valve andigniter are immediately energized andthe heater 18 is i also energizedfor causing the timer to begin functioning. As the bimetal' element 10becomes heated it warps to the left, first closing the blower switch13-14 for placing the blower into operation, and later opening theignition switch12-18 for placing the igniter out of operation. Theblower at this time lsenergized through an independent circuit extendingfrom line wire 88 through wire 90, contact 14, switch blade 13 andblower 5 to line wire 85. When the room thermostat becomes satisfied itdeenergizes the oil same manner as described when the room thervide forburning residual fuel under forced dratt.

If this sequence of operation provided by the limit control locationillustrated is not desired.

. the limit control may be connected. in series with the room thermostator in series with the relay.

Figures In Fig. 2 a modified'iorm of control systemds illustrated for.obtainingthe same sequence of valve and the timer heater 18, whichpermits the timer to begin cooling. Shortly thereafter the"'bimetalelement 10 moves to the right for r cl sin: the igniter switch 12-11. Atthis time the operatin r member 1| is out of engagement it the switchblade 13 and consequently the blower switch remains closed and theblower con tinues to operate. After a substantial period of time whichpermits the residual oil to be burned,

the member 1| engages switch blade 13 for open ing the blower switch andplacing the blower out of operation; I

From the foregoing description it will be apparent that the presentinvention provides an extremely simple control system for a fuel burnerhaving an igniter and/or a blower, the system also maintaining theblower in operation for a period of time after the oil supply isdiscontinued, for properly burning the residual oil. It

- will also be apparent that the present invention provides an ignitercontrol arrangement which insures that combustion of the fuel willalways take place. While the invention is particularly applicable to apot or vaporization type burner, certain features of the invention areof broader application. Inasmuch as many changes may be made withoutdeparting fromthe scope of the present invention, it is desired to belimited only by the a pended claims.

What'is claimed is:

1. In a control system for a pot type oil burner having an igniter, thecombination of, an oil valve for controlling the flow of oil to theburner pot, control means responsive to the demand for heat from theburner for opening and closing said valve and controlling said igniter,said control means acting upon a demand for heat to open the oilvalveand place the igniter in operation, an igniter controller having a firstposition in which 4 the igniter is rendered operative under the controlof said control means and a second position in which the igniter isrendered inoperative, slow acting means controlled by said control meansfor moving the igniter controller from its first position to itssecondposition a period of time after opening of the oil valve upondemand for heat by the control means and for returning said ignitercontroller to its first position a period of time'after the controlmeans becomes satisfied, said slow acting means being timed to returnthe igniter controller to its first position before the oil supplied tothe burner pot by the valve becomes exhausted.

2. In a control system for a fuel burner having from the burner. an oilline, a fuel valve disposed in said oil line a substantial distance fromthe burner pot, whereby a substantial amount of oil is permitted to fiowto the burner not after the oil valve is closed, valve operating meansincluding a device for controlling the oil valve, said valve operatingmeans being controlled by V the control means and acting to open the oilto render the igniter inoperative after a timed an igniter, thecombination of, control meansresponsive to the demand for heat, a fuelvalve for controlling the flow of fuel to the burner, valve operatingmeans including a first slow acting device forcontrolling said fuelvalve, said valve operating means being controlled by the control meansandacting to open the fuel valve in response to a call for heat bythecontrol means and to close the fuel valve a period of time after thecontrol means becomes satisfied, a

- second slow acting means having a first position rendering the igniteroperative under the control ofsaid control means and a second positionfor rendering the igniter inoperative, said second slow acting meansbeing controlled by said control means and moving from its firstposition to its second position when the control structed and arrangeda) return to its om posimeans effects tion before the ,first slow actingclosing of the fuel valve.

s. Ina control system for a pot type its burn-' 'er having an igniter,the combination of, control means responsive to the demand for heatafter a further period of time;

period and returning from its second position to its first position aperiod of time after the control means becomes satisfied, said slowacting means being constructed and arranged to return to its firstposition before the oil in the oil line between the oil valve and burnerpot becomes exhausted.

4. In a control system for a burner having fuel feeding means, anigniter and a blower, the combination of, control means responsive tothe demand for heat from the burner, said control means acting upon callfor heat to place the fuel feeding means and igniter into operation andacting when the demand for heat is satisfied to place the fuel feedingmeans out of operation, and timing means controlled by said controlmeans .for controlling the blower and igniter, said timing means beingconstructed and arranged to place the blower into operation a period oftime following the demand for heat, and then placing the igniter out ofoperation, said timing means also being arranged to first render theigniter-operative under the control of said control means and then placethe blow- 'er out of operation when the demand for heat is satisfied.

5. In a control system for a burner having an electrically operatedblower and an electrically operated igniter, the combination of, anelectrically operated fuel valve, a circuit for the fuel valve, acircuit for the igniter, condition responsive switching mechanisminterposed in said circuits and operative to close said circuits upondemand for heat, a normally closed ignition circuits, said timing meansbeing constructed and arrangedto act a predetermined period of timethereafter to first close the blower switch and then open the ignitionswitch, said timing means alsobeingarrangedtoactuponopeningofthe valveand igniter circuits to reclose the ignition switch before the oilsupplied by the oil valve. be-

comes exhausted and to open the blower circuit VIRGIL aoanss 'ra'rs.

